Ultragenyx Pharmaceutical Inc., a biotechnology company focused on developing treatments for rare and ultra-rare genetic disorders, announced that the FDA Office of Orphan Products Development has granted orphan drug designation for UX001 for the treatment of hereditary inclusion body myopathy (HIBM). UX001 is an extended release formulation of sialic acid (SA-ER) intended as a substrate replacement therapy for HIBM, a severe, progressive, genetic neuromuscular disease caused by sialic acid deficiency. Ultragenyx initiated the first study in humans of this disease in August 2011, a phase 1 pharmacokinetic and safety trial of UX001, from which data is anticipated later this year.

"The FDA's decision to grant UX001 orphan drug designation is another important milestone for our HIBM clinical program and underscores the urgency of the need for a safe and effective treatment for this rare and debilitating neuromuscular disease. We look forward to continuing to work cooperatively with the agency to advance this potentially important new therapy through the clinical testing and regulatory process, and appreciate the support from patients, families and physicians throughout the HIBM community," said Emil D. Kakkis, MD, PhD, chief executive officer of Ultragenyx.  

The Orphan Drug Designation program provides orphan status to drugs and biologics which are defined as those intended for the safe and effective treatment, diagnosis or prevention of rare diseases/disorders that affect fewer than 200,000 people in the US Among the benefits of orphan designation in the US are seven years of market exclusivity following FDA approval, waiver or partial payment of application fees, and tax credits for clinical testing expenses conducted after orphan designation is received.

HIBM is also known as distal myopathy with rimmed vacuoles (DMRV) and Nonaka disease. To harmonize the naming of this disease, medical experts have now designated the disease to be called "GNE myopathy." GNE is the abbreviation for the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase gene, which is defective in patients with GNE myopathy. HIBM, or GNE myopathy, is a severe, adult-onset muscle disease caused by a deficiency of an enzyme in the first step of sialic acid biosynthesis needed for the modification of proteins and fats. Patients with HIBM/GNE myopathy typically begin to have weakness and abnormal walking at 18 to 30 years of age. Over the ensuing 10 to 20 years, many patients progressively lose significant functional ability and become wheelchair-bound. There are no current treatments for this disease.

UX001 is an extended release formulation of sialic acid that should allow the maintenance of steady levels of sialic acid after oral administration.  The sialic acid replacement therapy is expected to restore the proper biochemistry of glycoproteins and glycolipids by allowing proper sialylation.  Data from an HIBM/GNE myopathy mouse model show a profound beneficial effect of sialic acid replacement therapy on the biochemistry, pathology and clinical outcomes of HIBM/GNE myopathy mice.

Ultragenyx is a privately held developmental stage biotechnology company committed to bringing life-enhancing therapeutics for patients with rare and ultra-rare genetic diseases, also known as orphan diseases, to market.